Various forms of miniature electronic buzzers have been proposed for use in small alarm clocks, timers, automotive and aircraft warning devices, and similar installations. There is always a variety of parameters to be considered in the design and large scale manufacture of such buzzers. The power and frequency requirements, audible output, sensitivity to changes in existing voltage, and ease and cost of manufacture, are all criteria that must be considered and balanced against each other. Considerable work has been devoted to achieving the best combination of these parameters.
In the prior art, typical miniature buzzers are disclosed in U.S. Pat. Nos. 2,977,418; 3,341,842; 3,530,463; and 3,564,542; and small buzzers employing piezo-electric devices are disclosed in U.S. Pat. Nos. 3,277,465; 3,331,970; 3,341,841; 3,569,963; and 3,697,983.